Gas-fired water heater with separable heat exchanger or detachably connected external water heater

ABSTRACT

A water heater, particularly but not exclusively for domestic use, is herein described and having removably secured thereto an external modulating gas power burner to heat the water in a separate tank portion. The two are easily separable from one another for service, repair or interchange. The hot water or a mixture thereof from the burner is circulated in a heat exchanger to transfer the heat to the tank water circulated from the water tank through the heat exchanger.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional application of continuation-in-partapplication Ser. No. 13/424,667, filed Mar. 20, 2012.

TECHNICAL FIELD

The present invention relates to water heaters, particularly but notexclusively, to domestic water heater tank to which is integrated amodulating gas burner and heat exchanger assembly and wherein theassembly is easily separable from the tank for service, repair orinterchange of the water tank.

BACKGROUND ART

It is known to integrate heat pumps with domestic hot water heaterswherein the hot gases are used in heat exchange with water circulatedfrom the hot water heater to provide an added heat source to heat waterand this usually results in complex devices integrated together in asingle unit. A disadvantage of such integrated devices is that becausedomestic hot water heaters utilize glass-lined casings whose life spanis usually short, and when such becomes defective it is necessary toeffect expensive modifications or to change the entire integrated deviceunit instead of only the hot water tank. Also, maintenance of integratedsystems can be expensive depending on its structure. Accordingly, thereis added fabrication costs and service cost when using integrated hotwater systems and this cost can sometimes obviate the projectedeconomical advantages of such systems. Such advantages include lowerelectrical energy consumption as it is less expensive to operate acompressor of a heat exchanger than the electrical resistive elements ofwater heaters. However, the refrigeration system provides cool airconditioning.

With gas-fired hot water heaters there is also considerable heat loss tothe environment through the exhaust flue. There is also a need toconsiderably reduce such heat loss.

Because water tanks of domestic water heaters have a relatively shortlife, it would also be beneficial to heat the water exteriorly of thetank whereby tank replacement would be less costly. Also, the waterheater could be serviced independently.

SUMMARY OF INVENTION

It is a feature of the present invention to provide a water heaterdevice with an integrated modular heat exchanger which substantiallyovercomes the above-mentioned disadvantages of the prior art.

Another feature of the present invention is to provide a water heaterdevice with an integrated modular heat exchanger and wherein the waterheater and heat exchanger are interconnected by detachable couplingmeans to disconnect the modular heat exchanger from the water heater forreplacement or servicing of the water heater or the modular heatexchanger.

Another feature of the present invention is to provide a two-portionwater heater device, one portion being the insulated water tank and theother an integrated modular heat exchanger with a modulating gas powerburner to heat the water and which is more efficient and less costly tooperate than stand-alone hot water heaters having resistive heatingelements.

Another feature of the present invention is to provide a domestic hotwater heater having an air-to-air heat exchange modular apparatusmounted on the top wall of the heater by detachable support means forrecovering heat form the exhaust flue to heat the air in theenvironment.

Another feature of the present invention is that because the water tankand modular heater are separable, replacement of the tank or heater canbe effected more quickly and requiring less expenditure andinconvenience to the owner.

According to a broad aspect of the present invention, there is provideda water heater comprised of a water tank for the containment of heatedwater and an external modular water heater detachably connected to thetank to heat water therein. The tank has a water inlet. A hot wateroutlet is provided in a top portion of the tank. A water supplyconnecting means and a heated water return connecting means is providedin a top portion of the water tank. The water supply connecting meanshas a water supply conduit extending to a predetermined location in thewater tank. The heated water return connecting means has a hot waterreturn conduit. The modular water heater has a gas-fired burner forheating a fluid circulated in a heat exchanger for heat transfercommunication with cooler water circulating between the water supplyconnecting means and the heated water return connecting means.

According to a still further broad aspect of the present invention thereis provided a water heater comprised of a water tank for the containmentof heated water and an external modular water heater detachablyconnected to the tank to heat water therein.

According to a still further broad aspect of the present invention thereis provided a water heater comprised of a water tank for the containmentof heated water and an external modular water heater detachablyconnected to the tank to heat water therein. The modular water heaterhas a gas-fired burner for heating a fluid circulated therein in aclosed conduit loop. The closed conduit loop has a portion thereofconnected in a heat exchanger for heating water circulated in anexterior conduit loop having a water intake end in communication withwater in a bottom region of the tank and a water outlet end in an upperregion of the tank.

BRIEF DESCRIPTION OF DRAWINGS

A preferred embodiment of the present invention will now be describedwith reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram showing an integrated water heater deviceand modular heat pump constructed in accordance with the presentinvention;

FIG. 2A is a perspective view, partly fragmented, of a gas-fired waterheater having an integrated modular air-to-air heat exchanger securedover a top wall of the water heater;

FIG. 2B is a further perspective view showing the water heater with afan connected to the casing of the heat exchanger to circulate the airthrough the heat exchanger and exhausted into the ambient air;

FIG. 3A is a further fragmented perspective view similar to FIG. 1, butshowing a differently constructed air-to-air heat exchanger secured overthe top wall of a conventional domestic water heater and wherein a fanis disposed in a top wall of the casing thereof to release heated airinto the ambient air in the vicinity of the water heater;

FIG. 3B is a top view showing the construction of the air-to-air heatexchanger;

FIG. 4A is a longitudinal fragmented side view showing the constructionof a water heater comprised of a water tank for the containment ofheated water and external modular heater detachably connected to thetank and supported over a top wall thereof and concealed within a casingextending co-linear with the housing of the domestic water heater;

FIG. 4B is a cross-section showing a heat exchanger comprised of aconcentric tube arrangement wherein hot gas or liquid within aconductive loop is in heat exchange with water circulated thereabout inan external conduit loop; and

FIG. 4C is a transverse cross-section of FIG. 4B.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the drawings, and more particularly to FIG. 1, there isgenerally shown at 10 a water heater device, herein a domestic hot waterheater device. A modular heat exchange apparatus, herein a heat pump 11is hereinshown detachably mounted on the top wall 12 of the hot waterheater 10 by detachable supports 13. The supports 13 are provided withsuitable detachable fastening means 13′ in a lower part thereof.

The domestic hot water heater 10 has an insulated glass lined orstainless steel lined inner casing 14. Water is introduced in the casingby a domestic cold water inlet conduit 15 and released through a diptube 16 connected thereto in a lower portion 17 of the inner casing 14.Hot water is extracted from the upper portion 18 of the inner casing,where the water is the hottest, by a hot water outlet conduit 19.Resistive heating elements 20 and 20′ are used to heat water in theupper and lower portion of the inner casing. The inner casing is alsoinsulated by an insulating foam material (not shown) introduced in thespace surrounding the inner casing and the outer shell 21. All of thisstructure is well known in the art.

As hereinshown, the modular heat pump 11 is provided with arefrigeration system including a condensation coil 26 which has arefrigeration conduit 26′ in which is circulated a compressible gas,such as Freon. The refrigeration conduit 26′ is in contact with a watercirculation conduit 27 in which cold water from the inner casing 14 isfed by a pump 28 which is secured to a supply conduit 29 connected to adip tube 30 whereby to extract cooler water from the lower portion 17 ofthe inner casing of the hot water heater 10. This supply conduit 29 issecured to the dip tube 30 by a detachable coupling means, such as aquick-connect coupling 31. As the cold water circulates through thewater circulation conduit 27, it is in heat exchange relationship withthe hot gas of the hot refrigerant in the conduit 26′ and is heatedthereby while cooling the gas. The refrigeration conduit 26′ and thecirculation conduit 27 may be concentrically mounted, as for example,for heat exchange.

The heated water from the water circulation conduit 27 exits thecondensation coil 26 through a hot water supply conduit 32 and is fed toa further dip tube 33 which terminates inside the inner casing 14 atapproximately two-thirds (⅔) distance down from the upper end of theinner casing 14 in a region where water is at an intermediatetemperature whereby to introduce hot water from the heat pump. Thehotter water propagates towards the top of the casing. The conduit 32 issecured to the dip tube 33 through another detachable coupling 34. Also,the cold water conduit 15 is secured to the dip tube 16 through afurther similar detachable coupling 35 and the hot water outlet conduit19 is also connected to the top portion of the inner casing by a similardetachable coupling 36 over the top wall 12 of the outer shell 21. It ispointed out that the detachable couplings 31, 34, 35 and 36 areconnectors capable of being disconnected and reconnected by a tradeperson whereby to easily disconnect the modular heat pump from the waterheater for the replacement or servicing of the water heater or themodular heat pump, if there is a need to disconnect them. The connectors31, 34, 35 and 36 may be screw-type or quick connect type connectors orconnectors that are soldered to the conduits 15, 19, 29 and 32, if suchconduits are made of copper. Any suitable connection means iscontemplated for detachment.

Because of the separable connections of both the hot water heater andthe heat pump, if the inner casing 14 becomes defective, a new hot waterheater 10 with its inner tank is replaced by the disconnection andre-connection of the quick connectors and the heat exchanger is securedon a new hot water heater. This can be done in a short time not toinconvenience the home resident. The previous hot water heater can thenbe recycled as only the inner casing needs to be changed and the heatpump can still be used.

As hereinshown, only basic elements of the integrated modular heat pump11 are illustrated. The refrigeration system includes a compressor 40and an evaporator coil 41 through which ambient air is pushed through byor drawn by a fan 25 whereby cooled dehumidified air 42 is expelled inthe space where the heat pump is located or in conduits to convey it toother spaces in a building. The refrigeration system also uses anexpansion valve 43 feeding the condensation coil 36. Such refrigerationsystems are well known in the art and only the basic components areshown in a general fashion.

It is also foreseen that the supply conduit 30 may be located exteriorlyof the hot water heater such as illustrated by phantom lines 30′ andeasily disconnected from the hot water heater 10 by a suitable fitting(not shown) but obvious to a person skilled in the art.

A controller module 50 is also provided to monitor water temperaturefrom temperature sensors 51 and 52 located at predetermined locationsinside the tank or inner casing 14 to monitor water temperature therein.Such is required to control the operation of the modular heat pump andthe resistive heating elements 20 and 20′ of the inner casing 14 tosatisfy user settings. A control pad 53 interfaces with the controllerand permits a user or service person to set the desired temperature ofthe water and the mode of operation of the system.

Although the integrated heat exchange apparatus is herein described as amodular heat pump, it is to be understood that other heat exchangeapparatus may be coupled to the hot water device, such as awater-to-water heat exchange apparatus having a coil with warmcirculation water therein and disposed like the condensation coil 26 inFIG. 1 for conduit 27. Such water-to-water heat exchange apparatus maybe from chiller application, i.e., large air-conditioning systems withcooling towers as found in high-rise buildings.

Referring now to FIGS. 2A to 3B, there will be described two examples ofa gas-fired water heater 55 and 55′ both of which have an integratedmodular air-to-air heat exchange apparatus 56 and 56′. As hereinshown,the water heater is comprised of an insulated water containment tank 57and 57′ for the storage of water to be heated. An outer skin or casing58 and 58′ surrounds the tank 57 and 57′ and spaced therefrom wherein aninsulating foam material (not shown) is disposed surrounding the watertank 57 and 57′. The tank as hereinshown has a bottom wall 59 and 59′under which there is located a combustion chamber 60 and 60′. A burnerassembly 61 and 61′ is located in the combustion chamber as is wellknown in the art. A flue passageway 61 and 61′ extends centrally in thetank and is in communication with water contained within the tank toheat the water therein. The passageway has an outlet end 62 and 62′which exits a top wall 63 of the tank and protrudes to the top wall ofthe outer skin or casing 58.

As shown in FIGS. 2A and 2B, the air-to-air heat exchanger 56 isconnected to the outlet end 62 of the flue passageway 61 and isconstructed to communicate hot flue gases exiting the outlet end 62 withheat conductive elements 64 in contact with the ambient air, hereinindicated by arrows 65 whereby to extract heat from the hot flue gasesand release the heat in the ambient air by the use of a fan 66 as shownin FIG. 2B. The air-to-air heat exchanger of FIGS. 3A and 3B is ofsimilar construction and reference to like parts will be describedsimultaneously hereinbelow. As hereinshown, the air-to-air heatexchangers 56 and 56′ are concealed in an outer casing housing 67 and67′. Openings 68 are provided on one side of the outer casing housing 67and 67′ opposite to the fan 66 whereby the fan displaces the ambient air65 across the heat exchanger. The outer casing housing 67, 67′ is ofcylindrical shape and substantially of identical size as the enclosureor outer skin 58 of the hot water tank.

The air-to-air heat exchanger 56, as shown in FIG. 2A, has a flue gasdiverting assembly 69 which has an inlet chamber 70 with a flueconnecting inlet 71. A plurality of conduits 72 are sealingly securedbetween the inlet chamber 70 and an outlet chamber 73 secured spacedthereabove. A flue connecting outlet 74 is secured to the outlet chamber73. A plurality of horizontally extending heat sink elements 75 aresecured spaced-apart to the plurality of conduits 72 to extract heattherefrom. These heat sink elements 75 are heat conducting plates orfins usually constructed of aluminum which is a good heat conductor.

As hereinshown, the inlet chamber is a bottom horizontal chamber withthe flue connecting inlet 71 being located centrally in a bottom wall 76thereof. The conduits 72 are connected in a top wall 77 of the bottomchamber and extend vertically thereabove. The outlet chamber 73 isspaced above the bottom chamber and the flue connecting outlet 74 isformed centrally with the top wall 78 of the outlet chamber. Ashereinshown, the flue connecting inlet 71 is also formed with the bottomwall 76 of the bottom chamber and extends centrally thereof for closefit sealing retention about the outlet end of the flue passageway andsupports the air-to-air heat exchanger thereabove and spaced from thetop wall of the outer casing 58 of the tank enclosure.

As shown in FIG. 2A, a blower 79 is secured to the flue conduit outlet74 to draw hot combustion gases from the combustion chamber through theflue passageway and direct them through the heat exchanger and thenexhaust them through conduits 80 to the outdoors.

As shown in phantom line in FIG. 2B, a conduit 81 can also be securedabout the fan 66 to direct the warm air extracted from the flue gas intoa remote location. Often the hot water tanks are installed in garagesand the conduit 81 can direct their recovered heat in a living space ofa building. The conduit 81 can also be connected to the ducting of afurnace where the fan of the furnace can direct the warm air releasedfrom the flue gases into the building structure. As also shown in FIG.2A, a condensate collecting conduit 82 is connected to a pan (not shown)but obvious to a person skilled in the art to collect condensate fromthe flue gases as they are cooled by the air-to-air heat exchanger anddirected the condensate to a drain (not shown).

Referring now to FIGS. 3A and 3B, the air-to-air heat exchangerapparatus 65′ is constructed slightly differently and has verticallydisposed spaced-apart inlet and outlet chambers 85 and 86 as betterillustrated in FIG. 3B and interconnected by the horizontally disposedplurality of conduits 87 secured between the inlet and outlet chambersand extend between opposed vertical side walls 85′ and 86′ thereof. Theflue connecting inlet 88 is secured to the inlet chamber 85. The flueconnecting outlet 89 is connected to the outlet chamber 86. Accordingly,the hot flue gases exit the flue passageway 61 and into the inletchamber 85 and then pass through the conduits 87 into the outlet chamber86 and out through the flue connecting outlet conduit 89 to exhaustoutside of the building structure.

As shown in FIG. 3A, a fan 90 is secured in an opening 91 formed in atop wall 92 of the outer casing housing 67′ for pulling ambient air 65′through the openings 68′ formed in the base of the outer casing housingunder the stack of heat exchange fins 93 secured in a spaced-apartarrangement around the conduits 87 to extract heat therefrom and releasethem into the environment by the fan 90. Heat is also extracted from thechambers 85 and 86 and all component parts in the air flow.

Referring now to FIG. 4A, there is shown the construction of a furthermodular water heater 100 which is comprised of a water tank 57″ securedin an outer casing 58″. Insulation material 101 disposed between thetank and the outer casing 58″.

Cold domestic water under pressure is fed to the bottom of the tank byinlet conduit 15 which connects to the diptube 16 and releases coldwater in the bottom portion of the water tank 57″. Hot water isextracted from the top portion of the water tank by outlet conduit 19 aspreviously described.

As shown in FIG. 4A, an external modular water heater assembly 102 isdetachably connected to the top portion of the water tank and outercasing top wall 103 by a suitable support frame 104 which is connectedto the top wall 103 at a bottom end thereof by support legs 105 fordisconnect from the top wall 103 of the tank. Other attachments are alsocontemplated as is obvious to a person skilled in the art. An outercasing housing 67″ surrounds the modular water heater assembly toconceal the components of the assembly therein. There are two pipecouplings, namely a water supply coupling 106 and a heated water returncoupling 107 connected to the top wall of the tank and exiting the topwall 103 of the outer casing for connection to the modular water heater.The water supply connecting coupling 106 is secured to a water supplyconduit 106′ which extends to a predetermined location in the watertank, herein to a lower region of the water tank to extract cooler watertherefrom. The heated water connecting coupling 107 is connected to ahot water return conduit 107′ which extends in a substantially centralregion of the water tank 57″ to return hot water therein.

The modular water heater assembly 102 has a gas-fired burner 108 of atype well known in the art for heating a fluid circulated in a heatexchanger 109 for heat transfer communication with the cooler watercirculating in a coil conduit loop 110 connected across the connectors106 and 107. A pump 111 circulates the cold water from the bottom regionof the water tank through the coil conduction loop 110. The fluid heatedin the gas-fired burner 108 circulates through a further conduit loop119 wherein heat from the hot fluid gas is extracted from the loop by aheat sink 112 and transferred to the coil conduit loop 110 to heat thecooler water therein. A pump 113 circulates the fluid within the conduitloop 114 and through the gas-fired burner 108. Heat from the gas-firedburner 108 is evacuated to the outdoors by an exhaust flue 115. The heatsink as hereinshown is formed by a stack of metal conducting fins 112′but the coupling means may be done by other heat transfer means such asshown in FIGS. 4B and 4C where a concentric arrangement of part of theconduit loops 110 and 114 wherein the conduit loop 114 has a largerdiameter than the conduit loop 110 as shown in FIG. 4B whereby heat fromthe conduit 115 is surrounded by the cooler water pumped from the watersupply conduit 106′ whereby a large volume of water surrounds theconduit 115 containing the hot fluid therein to extract heat.

The external modular water heater 102 is a low pressure modulating gaspower burner. A controller device 116 is connected to a temperatureprobe 117 to monitor the temperature of the water in the tank andoperates the gas power burner to maintain a desired hot watertemperature setting. The high efficiency design of the heat exchanger(90%+) allows combustion gases to condensate and this condensate isevacuated from the heat exchanger through a drain line not shown in FIG.4A, but obvious to a person skilled in the art. The input modulation isaccomplished using a variable speed premix combustion blower 120, aventuri (not shown) and a gas valve 119′. The heat transfer fluid fromthe gas-fired burner could be a mixture of glycol and water or any othertype of heat transfer fluid. It is also pointed out that the watersupply conduit 106′ may be an exterior conduit such as shown in phantomlines at 106″ which is secured to the bottom region of the tank.

Broadly stated, the water heater combo as shown and described in FIG. 4Acomprise essentially a water tank 57″ for the containment of heatedwater and an external modular water heater 108 detachably connected tothe tank to heat water therein. As herein described, the modular waterheater has a gas-fired burner for heating a heat transfer fluidcirculated therein in a closed conduit loop 114. The closed conduit loophas a portion thereof connected in a heat exchanger arrangement with aconduit loop circulating cold water from the bottom region of the tankand returning it to a mid-region of the tank after extracting heat fromthe conduit loop 114. Therefore, if there is a need to change the tankafter its useful life, it is simply disconnected from the gas-firedburner assembly and a new tank reconnected by disconnecting four pipecouplings and support feet of a support frame for the burner assembly.Suitably, the gas-fired burner can be disconnected for service orreplacement.

It is within the ambit of the present invention to cover any obviousmodifications of the water heater device integrated modular designs asillustrated and described herein. For example, although the modular heatexchanger or heater assembly is hereinshown resting on the top wall ofthe hot water heater by disconnectable supports 13, it is also foreseenfor certain of the embodiments disclosed herein that the modular heatexchanger or heater assembly can be suspended from a ceiling or attachedto an adjoining wall adjacent the water tank or water heater 10. Also,all of the conduits may be flexible conduits as now commonly utilized inplumbing and provided with appropriate quick disconnect connectors toconnect to the hot water heater 10. Although the hot water heater 10 ofFIG. 1 is shown with two resistive elements, a third or more resistiveelements could be incorporated inside the inner casing depending on theperformance required for the supply of hot water. The hot water devicemay be constructed for commercial applications and wherein the hot waterreservoir may be of a larger capacity than domestic water heaters.

We claim:
 1. A water heater comprised of a water tank for thecontainment of heated water and an external modular water heaterdetachably connected to said tank to heat water therein, said tankhaving: (i) a cold water supply connecting pipe coupling secured to atop wall of a casing of said water tank and connected to a water supplyconduit extending inside said water tank and terminating in a lowerregion of said water tank, (ii) a heated water return connecting pipecoupling secured to said top wall for extracting hot water from an upperportion of said tank, (iii) an external modular water heater supplycoupling secured to said top wall and to a water supply conduitextending inside said tank to said lower region of said water tank wherethere is cooler water, and (iv) an external modular water heater waterreturn conduit and associated coupling secured to said top wall and to aconduit extending to a substantially central region inside said watertank, said modular water heater having a gas-fired burner for heating afluid circulated in a heat exchanger for heat transfer communicationwith a coil conduit loop having a first end connected to said externalmodular water supply coupling connected to said water supply conduitextending to said lower region of said water tank, and a second endconnected to said external modular water heater return coupling, a pumpfor pumping water from said first end through said heat exchanger andout said second end, all of said couplings secured to said top wallbeing disconnectable to opermit removal of said external modular waterheater from said water tank.
 2. A water heater as claimed in claim 1wherein said heat exchanger comprises a coil assembly having a firstcoil in which said fluid is heated by said as fired burner and iscirculated, and a second coil in which said cooler water circulates, andheat transfer coupling means secured to said first and second coils totransfer heat from said first coil to said second coil.
 3. A waterheater as claimed in claim 2 wherein said heat transfer coupling meansis a heat sink comprised by in a stack of metal conductive fins fortransferring heat from one coil to the other.
 4. A water heater asclaimed in claim 2 wherein said heat transfer coupling means isconstituted by said second coil having a larger diameter than said firstcoil and being secured concentrically over at least a portion of saidfirst coil in spaced-apart relationship for permitting circulation ofsaid cooler water about said at least a portion of said first coil toextract heat therefrom.
 5. A water heater as claimed in claim 2 whereinsaid external modular water heater is a low pressure modulating gaspower burner, and a controller device connected to temperature sensingmeans associated with said tank for monitoring the temperature of waterin said tank and operating said gas power burner to maintain a desiredhot water temperature parameter setting.
 6. A water heater as claimed inclaim 1 wherein said external modular water heater is an independentmodular unit supported above said top wall of a casing of said watertank by a disconnectable support frame.
 7. A water heater as claimed inclaim 1 wherein said water supply conduit is a diptube which extends tosaid bottom region of said tank.
 8. A water heater as claimed in claim 1wherein said water tank is a domestic water heater, said water tankbeing an insulated water tank contained in an outer casing.
 9. A waterheater as claimed in claim 8 wherein said modular water heater issupported over a top wall of said outer casing and wherein an outercasing housing surrounds said modular water theater.